We consider a cooperative diversity system with two users and a single destination. Let us assume user 1 acts as a source and user 2 relays the data received from user 1 to the destination. In time frame 1, user 1 transmits the data 
to the destination directly as well as to the user 2. In time frame 2, user 2 decodes the data 
and forwards as 
to the destination as shown in the
are the received complex baseband signals at the destination and user 2 respectively in time frame 1. 
is the complex baseband signal at the destination in time frame 2. 
are complex fading gains from user 1 to destination and from user 1 to user 2 respectively. 
is the complex fading gain from user 2 to destination. 
is the transmitted BPSK symbol of user 1 having energy
, 
and 
are the addi-
tive white Gaussian noises from user 1 to destination and from user 1 to user 2 respectively. 
is the additive white Gaussian noise from user 2 to destination. 
are the independent zero-mean complex circular Gaussian random variables having variances. 
respectively and are independent of the additive noises. 
are independent and identically distributed zero-mean complex circular Gaussian random variables with variance
, i.e. having a 
distribution.
at user 2, which can be expressed as
, which can be expressed as
denotes the signum function. Let 
denotes the final decoded symbol at the destination using SC is given by
denotes the output of the EGC, which can be expressed as
is the weighting factor of EGC, which can be given by
for
. 
are the magnitudes of the weighting factors which are same and do not depend on the signal-to-noise ratio (SNR) values of the communication links.
denotes final decoded symbol at the destination using MRC is given by
is the weighting factor of MRC, which can be expressed as
is the variance of
, phase 
for
.
, obtained by the coherent detection is given by
denotes the Gaussian Q-function.
, we obtain SEP in the non-cooperation mode as
and 
denote the instantaneous SNR of the user 1 to user 2 link and instantaneous SNR of the user 2 to destination link respectively, given by
and 
denote the average SNR of the user 1 to user 2 link and average SNR of the user 2 to destination link respectively, given by
, the disjoint events which lead to a correct decision can be enumerated as
conditioned on 
and 
can be written as
and 
are defined as
and
, we obtain the probability of the event 
as
can be written as
and 
under the condition 
can be simplified into
and 
are defined as
can be similarly written as
and 
under the condition 
can be simplified into
. Therefore the end-to-end SEP, which is denoted as 
in cooperation mode can be expressed as
the expression (36) can be approximated as
value increases. From the 
and 
is varied between 5 to 15 dB. We also observe similar increase in performance when 
and 
is varied between 5 to 20 dB. From the 
The diversity range offered by MRC is approximately increases by 5 dB. SEP values of EGC are almost close to the MRC because both the schemes are coherently combining the signals at the destination. The performance of the MRC, EGC, SC is almost similar after the points of intersection 
and 
.
values. We also compared the MRC, EGC, SC with each other in providing better diversity. The obtained simulation and computation results